The Impure Prince
by Saamon-sama
Summary: Due to a near impossible twist of fate a child is born as his own human familiar, the first changeling not rooted to the laws of the Darklands. The "Prince of Enchanters" was in fact a Prince. So with the power of Merlin flowing in his son's veins, Tobias must help Severus master control of his troll form, so that none may discover his existence.


**The Impure Prince**

AU crossover inspired by the animated first season of Dreamwork's _Trollhunters_ by the brilliant Guillermo del Toro.

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 **Notes: Darklands = Darklanders?** _This chapter may be a bit confusing, but know that I am writing this from Severus' dad's perspective. Severus' own point of view will only eventually be shown if I end up continuing this story._ **  
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 _ **Please review** all thoughts, questions, and reactions you may have had_. I promise to respond to all registered reviews. **:) If I do continue this, it will eventually become a Sevmione tale.**

What got me thinking about this crossover is the fact that to activate his magical armor, Jim has to say, _"For the glory of Merlin, daylight is mine to command."_ And I just thought, _"Merlin?"_ And so here we are.

 **Disclaimer: Nothing is mine. Absolutely nothing. **

_I'm just testing the waters. This fic will stay a one-shot for now, depending on feedback._  


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He'd gone four years believing the child he was raising wasn't his.

What else was he expected to believe? Impure, more commonly known as changelings, were born through performing painful, unpredictable alchemy on a newborn troll. The infant trolls were then forced to grow and learn strictly on a mental level, never to age until their human familiar was born in the above world. Often times, hundreds of years would pass before one's familiar came into creation. Snape himself had been very lucky. He'd only had to wait sixty-six years before Tobias Snape the human had been born.

His cousin Stricklander, on the other hand, had been alive since before Gunmar's fall over two decade ago. The last he'd heard from him had been before Snape had run away from his host parents as he fled from a shidokh, and even then Stricklander had still been the size of an infant troll waiting for his fleshbag familiar to be born.

Many changelings wound up staying in the Darklands, unless ordered otherwise by Gunmar, preferring the company of fellow trolls and the comfort of their own rougher bodies, despite the constant degradation of being called _Impure_. Others, like him, craved for the sun and so struck bargains with the goblins to be switched with their human familiar under the guise of doing Gunmar's bidding. He'd never before heard of changelings being born naturally.

The vey idea of a _pure_ Impure was laughable.

After the nurses had taken Severus away, (For circumcision and baby shots and the whole caboodle. Not that Snape was religious, but his host parents had raised him as such and he felt continuing the hygienic tradition with his child was the least he could do to honor them, what with having stolen their actual child's rightful life and then running away from home.) and Eileen napping away after having completed the proper skin-to-skin mother and child bonding, Snape had felt he'd truly left the Darklands behind. He was Tobias Snape, through and through, and he had a son. A human son.

Then a nurse returned, gently placing a quiet Severus into his awkward arms, and Tobias finally allowed himself to embrace the euphoria of fatherhood. Elation and pride and warmth filled his chest as he gazed down at the little being he'd played a hand in creating.

He had ten little fingers, and ten little toes. When he sleepily blinked before falling back into a doze, he'd revealed eyes so black, Tobias wondered if they'd eventually lighten to Eileen's unique grey, or if light would one day shine in them to reflect his own chocolate brown shade.

He was soft and fragile and radiated heat. He was a small, pathetic little fleshbag that Tobias wanted to protect from the world. He was human, destined to feel the warmth of the sun, and Tobias couldn't be happier for his child.

Then he'd said hello to his little baby boy, ever so softly.

And in the span of a blink, Severus' eyes had opened and glowed with silver irises set in heart-stopping black sclera before turning to a natural black in white.

Tobias nigh dropped the child.

Frantically with a quiet sort of desperation, he undid the towel wrapped around the babe enough so as to see its nethers.

He stared in confusion.

Then he tightened the towel back up.

"Couldn't be switched late enough to avoid that procedure like me, eh?" He chuckled humorlessly, as dread settled in his gut and he began to feel a pang of _want_ in his chest. Had his arms turned to stone or was the child suddenly heavier?

By all the colors of hell he _missed_ his boy, the child he'd barely even met before it was taken from him.

He almost asked the babe if it was Stricklander, his unfortunate older cousin of a troll who had a nigh unhealthy love of history, of all possible subjects. What irony it would have been, to have a child, only for it to be the familiar of his fellow Impure relation. But he held his tongue, knowing the possibility was impossible. For all changelings, (those who survived their painful transformation that is,) were also all orphans, be it by unfortunate circumstances or by Gunmar's will, and thus named after the name of their familiar, the only hint any of them had to who they could one day replace.

Not to mention, Stricklander had eyes of ruby and yellow, like Tobias' own.

Nothing happened after that, no matter the minutes that passed in silence as Tobias sat there, frozen as he stared at the fidgetting babe.

If not for the image burned into his retina, Tobias might've thought he'd simply imagined it.

What he wanted to do, really, truly wanted to do, was grasp the child about the neck, and shake him, demanding what had been done with his boy. He wanted to shout and growl, threaten the child into morphing into their changeling persona and tell them they had no choice but to live out the rest of their days in the Darklands if they wanted to continue living.

He wanted to know how _the bloody fuck_ a goblin had managed to sneak into the birthing ward and kidnap his baby within the span of minutes that it took for nurses to clean him up.

He wanted to transform into his own troll visage, a form he had not donned since he had run away from home to avoid marrying the girl his fleshbag parents had arranged for him to be with, and raze the building to the ground.

What he ended up doing, however, was stare in a numb state of shock, vaguely trying to remember if he'd ever met a troll with eyes of silver and black, as Eileen awoke to the sound of (what she believed to be) her newborn son fussing as his father uselessly held him.

"Tobias?" Eileen inquired, reaching out to the fussing infant.

"You should be impossible," Tobias murmured, as he stared blankly at the baby even as Eileen maneuvered him to her breast. She cooed in motherly wonder over the child's already open eyes.

The child he'd created was his, not the real human Tobias Snape's. He couldn't fathom the possibility of his baby being a familiar match for another changeling. It should have been impossible!

Eileen, mistaking his murmured horror for awe, smiled as she looked at the nursing babe.

"But he's real, Toby. And he's ours."

If only he'd believed her, his mysterious Eileen who's sharp tongue and quick wit had endeared him to her in a way no other female, human or troll, ever had before.

Had he listened to her, perhaps these past four years could have gone better. He'd distanced himself from the child, fearing any slip in exposing himself would have brought on Gunmar's wrath; for mating with a human certainly wasn't something to boast about back home.

Especially if the troll in charge wanted all the humans dead.

And because he distanced himself from the babe, his relationship with Eileen had strained and cracked and crumbled somewhere along the way. She couldn't understand why he refused to acknowledge their child, and he couldn't bring himself to explain to her that he believed the boy wasn't the one she'd given birth to.

He didn't want to open that jar of gnomes. He didn't even know where he'd start explaining himself.

Then came today, just a couple weeks after his son's fourth birthday, where things went pear-shaped and everything turned on its head.

With a bang, Eileen had shoved her way into the house, slamming the door closed behind her.

"Bloody hell, woman!" Tobias growled, his head throbbing from hangover as he set his glass of water down and staggered out of their little kitchen. "What's got your ni-"

"TELL ME WHAT YOU ARE, AND WHAT YOU HAVE DONE TO MY BOY!" Eileen screamed.

Ears ringing and eyes wide, Tobias felt his pulse pound even as comprehension and time turned to molasses. Never before had Eileen screamed at him. In all honesty, he was the one to shout and raise his voice whenever emotions got out of hand. Eileen spoke sternly, and her voice would grow deeper with anger before stuttering away into tears.

Her hand rose as if to slap him, before twitching back behind her.

There was one thing he could proudly say about their whole mess of a marriage; as angry as either of them ever grew, they'd never resorted to physical attacks.

Blearily, through the haze of his hangover, Tobias realized Eileen was brandishing something in her right hand.

"Is that... are you threatening me with a bloody twig?" He asked, a mad sense of humor bubbling up within him.

"Bloody twig?" She repeated, pointing the dark stick at the point between his eyes. "I just had to _obliviate_ half of the bloody shoppers at the grocers this morning with this _bloody twig_ because your son TRANSFORMED WHEN SOME OF THE BLOODY STREET RATS THREW FUCKING STONES AT HIS HEAD!"

Tobias froze, all sense of burgeoning humor gone as Eileen's irate inhalations filled the sudden void of sound. Silently, he wondered why this argument couldn't have happened when he was more sober. The wake of Eileen's screeching left the irritating sound of tinnitus in his sensitive ears as he carefully rewound her words in his head.

"Oblivi-what? He's not my-"

"DON'T YOU DARE!" She took a breath. "He _is_ your son! He's _our_ son!" Eileen choked, a sob in her throat. "He _is_ supposed to magical... But n-no blood of mine c-could have ever made him like-" Tears dripped from her lashes as her emotional turmoil finally rid her of her voice.

Suddenly the molasses of his brain melted away as comprehension dawned on him. Leaving the sight of his wife's dripping cheeks, his eyes trailed down her left arm to the hand hidden behind her back. The edge of the boy's overlarge grey tee peeked out from behind her skirt.

"Step out and let me see you, boy," he said, voice automatically taking on the commanding tone he'd grown used to using around the child.

After a moment, Eileen's tear-stained glare unwavering in their assault on his person even as she made no motion to hold back the child, the boy walked into view. Tobias froze, feeling as if he'd been hit by a wall as a chill ran up his back and his eyes widened at the image that greeted him.

For the second time in his life he was granted the unsettling sight of silver irises set into onyx sclera. Silk black hair had morphed to downy feathers, tufting up in the humidity of a UK morning. Black horns reminiscent of those belonging to Rocky mountain goats jutted up from the boy's forehead while his nostrils had moved and lengthened to slits on the sides of his nose. Six sharp fangs peeked over his lips; as if attempting to grotesquely stitch shut the very mouth from which they came from. What was once soft and pale flesh had thickened into an unmalleable dark grey hide, smooth and hard as marble, chiseled with markings that would no doubt glow bioluminescent blue in any moments of emotional excitement. Torn through the fabric of the boy's back were the fledgling beginnings of what would one day be a velvet wingspan four times as long as however tall he would grow. For now however, they were at the physically improbable proportions like that of wings on a bee.

It said much about Eileen's love as a mother, for despite the living nightmare that the boy had suddenly taken the form of, still she held his hand-turned claws- in her unwavering grasp.

And it was then that Tobias realized he'd made a huge mistake. There was no longer a doubt in his mind that Severus was his son.

For no troll, dead or alive, had such perfectly _human_ proportions. None of his limbs had grown or shrunken, lengthened or shortened, despite the transformation. Unless Gunmar suddenly began valuing academics, there was no way the process of creating changelings had changed with such physically unimportant details in mind.

As a human, Severus looked a perfect blend of Tobias Snape and Eileen Prince.

As a changeling, Severus was the perfect blend of Eileen the human, and Snape the troll.

So much for the non-existence of pure changelings. It seemed his child was a special case.

The silence broke.

"Tobias," Eileen spoke. Again she brandished her carved stick at him as she simultaneously pulled Severus to stand behind her and Tobias choked, catching himself in the throes of manic laughter. He pressed a hand to his face, fingers partially covering his right vision as he smiled in self-deprecation.

Severus peeked around his mother's skirt, silver eyes aglow with fear and confusion and questions as he stared up at the father he barely knew.

"I've royally fucked things up, haven't I?" Tobias felt a headache coming back on, this time due to his mind working through his packed away memories as fast as it could, trying to figure out, find just a hint of a clue, of how his son could legitimately exist. A million questions he should have pondered years ago surged through his mind with the re-realization that he'd created a functioning child with a human.

Trolls did not mate with humans. They never had, even before the rise of Gunmar, before the time of strife between the species, before humans chased trolls underground with their awakening of fear against beings that were essentially monsters who ruled the shadows. Physically, anatomically, and genetically speaking, such relations between the species was impossible. Then came the creation of changelings, a project devised by Gunmar in his quest to take back the above lands.

By becoming half-human, forging connections with human familiars and stealing their above ground lives, trolls could infiltrate the land and attack when humans least expected it. But even with human bodies, a changeling could not reproduce with a human, for their very dna was still that of a troll's.

The very thought of there once being true human-troll hybrids was stuff of myths and fools-tales. Stories told to younger changelings by their older orphan siblings in a bid to overlook the shame of being turned into something essentially less than a troll.

An old memory of his cousin resurfaced. What had Stricklander once said? _"Don't let their words get to you, Snape. You and I, we are but stolen princes from our respective races! In fact, they've unwittingly made us even better than the rest of them! For we halfbreeds have the ability to live in sunlight! In the time of Merlin, halfbreeds like us had dwindled down to one family line, that of Merlin himself. With his fall, Lord Gunmar took charge and the war with humans and fellow trolls began, ultimately resulting in our underground exile. But just you wait, for I promise that one day, after my familiar is born, I will lead our brethren back to our former glory!"_

At the time, Snape had believed those words to be nothing more then epic lies spoken to soothe his damaged esteem. Then his own familiar had been born in the following years, granting him access to the above world before Stricklander, and the tale had fallen to the wayside.

Perhaps there may have been a shred of truth to the story?

"By Merlin, I don't know what to think," Tobias muttered. Eileen visibly flinched, redirecting his gaze from Severus to her. She looked shocked.

"Merlin? What do you know of Merlin?"


End file.
